These files contain binlog events in ROW format representing the failed transaction. That means that the slave thread was not able to apply one of the transactions. For each of those file, a corresponding warning or error message is present in the mysql error log file. Those error can also be false positives like a bad DDL statement (dropping a table that doesn’t exists for example) and therefore nothing to worry about. However it’s always recommended to check these log to understand what’s is happening.

To be able to analyze these files binlog header needs to be added to the log file.

In this example DROPTABLE statement was executed on a table that doesn’t exist.

galera.cache

This file is used as a main writeset store. It’s implemented as a permanent ring-buffer file that is preallocated on disk when the node is initialized. File size can be controlled with the variable gcache.size. If this value is bigger, more writesets are cached and chances are better that the re-joining node will get IST instead of SST. Filename can be changed with the gcache.name variable.

gvwstate.dat
This file is used for Primary Component recovery feature. This file is created once primary component is formed or changed, so you can get the latest primary component this node was in. And this file is deleted when the node is shutdown gracefully.

First part contains the node UUID information. Second part contains the view information. View information is written between #vwbeg and #vwend. View information consists of:

view_id: [view_type] [view_uuid] [view_seq]. - view_type is always 3 which means primary view. view_uuid and view_seq identifies a unique view, which could be perceived as identifier of this primary component.

bootstrap: [bootstarp_or_not]. - It could be 0 or 1, but it does not affect primary component recovery process now.